A high-pressure coupling with the aforementioned features is described in EP 0 853 743 B1. Couplings of this type with a plug part having an inner and an outer channel and with a correspondingly designed receptacle part are required, in particular, for connecting a hydraulic drive element to a hydraulically driven device, for example when a drive element in the form of a hydraulic pump is not only connected to a device in the form of a tool by means of a pressure line, but also by means of a return line. In such a high-pressure coupling, it is problematic that the fluid enclosed in the inner channel of the plug part by the closing cone may heat up in the decoupled state and therefore lead to such a pressure increase that it becomes difficult to couple the high-pressure coupling by inserting the plug part into the receptacle part because the closing cone in the inner channel of the plug part needs to be moved against the increased pressure.